AIT, which is an ingredient of wasasbi, has a superior antimicrobial action such as biocidal, antibacterial and antifungal actions, and shows no harmful effect on human beings. Accordingly, its usefulness as a biocidal agent for foodstuffs and the like has been drawing attention.
AIT itself has a peculiar, strong and sharp smell, and is disadvantageous in that the strong sharp smell adheres to food and the like when used at a high concentration. It is therefore required to effectively exhibit the antimicrobial action in a least possible amount.
Fortunately, AIT vapor from the highly volatile AIT, too, has a strong antimicrobial effect, which allows effective exertion of the antimicrobial action to every corner with only a small amount of the vapor.
Due to the extremely high volatility of AIT, however, the use thereof as it is results in high AIT vapor concentration reached in a short time in the atmospheric gas with which the objects to be treated with the antimicrobial agent are brought into contact, which in turn leads to disadvantageous results that the smell attaches to the objects to be treated, adverse influences are caused by the infiltration of the AIT vapor into the objects to be treated, and the retention of the effects becomes inferior.
For the AIT to be effectively used as an antimicrobial agent, a method is desired which enables free control of the release speed of the AIT vapor and free control of the AIT vapor concentration in the atmospheric gas with which the objects to be treated with the antimicrobial agent are brought into contact, according to the objects to be treated and treatment method. In addition, an antimicrobial agent capable of keeping the effective concentration of AIT in the atmospheric gas for a long time is also desired.
In particular, an antimicrobial agent and a method capable of maintaining a certain release speed for a long time without being influenced by the residual AIT amount are desired. Also, an antimicrobial agent and a method are desired which permit free and easy control of the release speed of the AIT vapor according to the system to be used.
Under the circumstance, agent forms have been proposed, such as an agent form wherein AIT is carried by a carrier such as zeolite, alumina, silica gel, pulp and paper to control the release speed of the AIT vapor, an agent form wherein AIT is packaged in a polyolefin film allowing high permeation of AIT vapor, and an agent form wherein AIT is packaged in a perforated film obtained by perforating a resin film impervious to AIT vapor.
An agent form wherein AIT is carried by a carrier fails to suppress the high volatility of the AIT, resulting in failure to control the release speed. When a film having a high AIT vapor permeability is used, the agent is defective in that a quantitatively constant release speed cannot be realized, since the release speed depends on the remaining amount of AIT, and that it cannot be practically applied to actual products requiring various release speeds, since release speed is controlled by the thickness of the film.
A perforated film is defective in that the release speed is influenced by the residual amount of AIT and constant release speed is difficult to achieve when AIT vapor is to be released by small portions, and that an agent showing little dispersion in release speed is difficult to manufacture.
As described above, a method permitting free control of the AIT vapor release speed without dispersion and a method permitting portionwise release of an effective amount of AIT vapor at a constant speed have not existed.